Tube socket assembly with corona disrupter

ABSTRACT

A cathode ray tube socket is provided which provides spark gap protection to terminal pins operating at selected high potentials through a distinct spark gap protection system, including a structure for disrupting the corona discharge track and minimizing the effects of corona discharge.

BACKGROUND OF THE INVENTION

Television picture tubes and particularly color television picture tubeswhich generally operate at high voltages, for example in the 15 KV to 30KV range, commonly generate undesired large transient voltages, noiseand corona within the tube. Such voltages must be controlled anddissipated in order to avoid conduction of these high voltages throughthe tube pins and tube socket contacts to other portions of thecircuitry associated with the tube; otherwise, these large voltages maydamage the tube, the tube terminals and may also couple to and damagethe associated electronics.

Many structures have been constructed to provide protection against suchlarge transient voltages and such structures have been utilized widelyin the commercial products. Note for example, U.S. Pat. No. 3,636,412 toSimovits and Dumas, entitled "Tube Socket Assembly"; U.S. Pat. No.3,733,522 to Simovits and Dumas, entitled "Arc-Over Protective Device";and U.S. Pat. No. 3,767,951 to Dumas and Simovits, entitled "ElectronTube Socket", all of which patents are assigned to the same assignee asthe present invention.

In order to dissipate the excessive voltages, cathode ray tube socketsare normally provided with some type of safety device in the form of agrounding apparatus. In the event that the pin is operating at anexcessive potential, the grounding apparatus permits a spark to jump orarc from the pin contact to ground. The foregoing prevents damage due toexcessive potential at the selected one of the pins by providing anon-destructive path to ground to thus eliminate the excessive overvoltage.

Commonly, one or more of the terminal pins is connected to highervoltage potentials than the other pins. Accordingly, the spacing betweenthe high voltage arcing terminal and the grounding plate are selected tobe greater than the space between the arcing terminals of the remainingpins and the grounding plate so that a higher potential is necessarybefore a spark can bridge the gap between the high voltage arcingterminal and the grounding plate. However, if a spark jumps from thehigh voltage arcing terminals to the ground plate, the potential of theground plate may rise so fast that it can be properly dissipated,thereby causing a second spark to jump from the ground plate back to oneof the other pin terminals thus seriously damaging the tube or theassociated circuit. Structures are thus provided for separatelyconnecting the high voltage arcing terminals to one grounding plate andgrounding the arcing terminals of the remaining pins to a separategrounding plate. The separate grounding plate tends to prevent thesparks from jumping from the high voltage pin to ground and then to theremaining pins.

The present invention further provides an improved tube socket assemblyoperating at high potentials including dielectric chambers wherein thehigh voltage pin arc-gap terminals are positioned. The high voltage arcchamber is separated and segregated from the remaining pin contacts andincludes a pair of controlled, uniformly spaced, high voltage spark gapscomprising two pairs of spaced hemi-spherical electrodes positioned inspaced relation to each other. The arc chamber is constructed to includea corona disrupter for minimizing the effects of corona discharge, aswill be explained.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings, wherein:

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the socket showing a socket base includinga low voltage spark gap system and a high voltage spark gap system, anda cover plate; and,

FIG. 2 is a cross-sectional view taken along the lines 2--2 of FIG. 1 toshow the construction of the corona disrupter for the high voltage sparkgap system.

DESCRIPTION OF THE INVENTION

FIG. 1 shows an exploded view of the inventive socket assembly 11comprising a base 12 and a cover 14 both of which are formed or moldedof a suitable relatively rigid insulative material such as plastic. Thesocket 11 includes a central passage 15 for mounting onto the terminalpin portion of the neck of a television picture tube, not shown. Theterminal pins generally labeled 16 extend downwardly for purposes ofconnecting the socket assembly 11 to suitable electrical and electroniccircuitry, as is known.

A conductor plate or ring 30, in substantially a semi-circle shape,conforms to the shape of a horizontal planar surface 22 on base 12 andis securely embedded as by molding, as is well-known, slightly beneaththe surface 22. Conductor plate 30 includes a terminal tab 31 forconnecting through an electrical lead 32 to ground reference. Openings33 are formed in surface 22 to selectively expose sections of the ring30 to provide one part of an arc gap as will be explained. The pins 16extend upwardly through suitable apertures 18 in base 12 and are bentover to have a portion 21 which extends horizontally over respectivespark gap openings 33 formed on surface 22. Pin portions 21 each includea dimple protrusion 23 which extends downwardly toward, but spaced from,ring 30. This provides the gap across which the low voltage arcingoccurs; as is well-known in the art.

The base plate 12 is generally in an irregular circular form, in planview, as is the entire assembly 11. The base 12 includes an upwardlyextending peripheral wall 29 which is irregular in height. The cover 14includes a peripheral wall 24 which mates with and encircles wall 29.The top 25 of cover 14 comprises two stepped planar surfaces whichconform to and provide a cover for base 12. The periphery of opening 15in base 12 includes one or more positioning notches 28 on itscircumference for properly indexing the socket assembly 11 on the neckof the associated tube.

The wall 24 of cover 14 includes vertically extending flexible latches26 which mate with, or are received by respective positioning catches orshoulders 27 formed on the periphery of the base 12.

The ends 33 of the pins 16A which extend to the periphery of opening 15provide electrical contact with the picture tube pins. Pin contact ends33 are bifurcated and are in the form of a spring-biased and centrallycantilevered structure similar to that described in U.S. Pat. No.3,733,522 assigned to the same assignee as the present invention.

A portion of base 12 extends vertically to form a housing 40 which issubstantially rectangular in plan view, on one side of base 12. Housing40 contains or encloses the high voltage spark gap devices, see alsoFIG. 2. Housing 40 is divided into two similar but separate chambers orcompartments 41 and 42 for housing or containing two distinct butsimilar set of spark gap electrodes. FIG. 2 shows a cross-sectional viewof the housing 40 and one set of the spark gap ball electrodes 43 and 44in chamber 41. Each ball electrode is substantially hemi-spherical andincludes a central nipple 60 which extends toward the other electrode;this provides a reliable spark gap initiating point. As seen in FIG. 1,the housing 40 includes a central air space 45 formed by dielectricwalls or barrier 46 and 47. The combination of the foregoing dielectricbarrier walls and the air spaces therebetween provide improved thermaland dielectric characteristics for the socket assembly 11 substantiallyaccording to the concepts described in U.S. Pat. No. 3,771,024 andassigned to the same assignee as the present invention.

The chamber 41 tends to maintain the atmosphere therein constant andstable such that the spark gap formed between the two opposed electrodes43 and 44 maintain a more constant arcing level.

It has been found that in certain multipotential applications, it isnecessary that the spacing between pairs of ball electrodes be adjustedto arc at different high voltage ranges. Thus, in the embodiment shown,ball electrodes 43 and 44 are spaced at a greater distance than theelectrodes in compartment 42 to accommodate a larger operating or arcingvoltage.

As shown in FIG. 2, the ball electrode 43 is embedded or formed in aplastic plug 51 which conforms to the periphery of the chamber 41, andis received in chamber 41. The electrode 43 is connected as by lead 62to the pin 16A and to the high voltage conductor 59. Chamber 41 includesan interior peripheral ledge 63 in which a hollow cup shaped ring spacer64 is positioned. Spacer 64 includes an inwardly extending rim 65 forpurposes to be described. The plug 51 including ball electrode 43 restson the top of spacer 64.

The lower electrode 44 is embedded in the bottom of chamber 41 and itslower surface is open to the surroundings. A vent hole 66 vents theinterior of chamber 41 to the surroundings. Electrode 44 is connectedthrough lead 67 to ground reference.

An important feature of the invention are the structures shown in FIG. 2which provides a corona disruption capability. Since corona precedesdielectric breakdown, a corona discharge adversely affects and changesthe selected and pre-established voltage breakdown or arcing potential,between the electrodes. It has been found that with ball electrodespositioned in chamber 41 having smooth sides, a corona discharge pathinitiated at one electrode extends or moves along the walls of thechamber and thence tends to reduce the arcing potential between the twoelectrodes. As shown by the dashed lines 69 in FIG. 2, the rim orshoulder 65 on spacer 64 provides an effective barrier which interruptsthe corona ionizing path track to thereby inhibit corona discharge. Ineffect the rim 65 provides a shadow area, indicated as X, fromelectrodes 43 or 44 to the wall of the chamber 41, which tends toinhibit establishing a corona discharge along the wall of the chamber.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art, that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention.

I claim:
 1. A tube socket assembly having spark gap means fordissipating high voltage transients occurring at the terminal pins of anassociated electron beam tube comprising, in combination:a housing ofdielectric material having an opening for receiving the terminal pins ofthe associated tube; high voltage spark gap means; dielectric meansforming a high voltage spark gap chamber within said housing forreceiving said high voltage spark gap means; ledges extending inwardlyfrom the walls of said chamber; a hollow spacer of dielectric materialand conforming to the interior dimensions of said chamber positioned onsaid ledges; said high voltage spark gap means including first andsecond ball-type electrodes; a plug module of dielectric material andconforming to the interior dimensions of said chamber positioned on saidspacer; said first electrode embedded in said plug; said secondelectrode mounted within said chamber in spaced relation to said firstelectrode, with the spacing between said electrodes relating to saidspacer; and said spacer having a rim extending inwardly into saidchamber for providing a barrier for interrupting the corona ionizingpath track to thereby inhibit corona discharge.